Solar Heater Overview:
I live in South Eastern Massachusetts, in the United States of America. I became interested in the prospect of solar heating of my swimming pool in an effort to 1) make my swimming experience more comfortable and 2) extend the swimming season.
My swimming pool gets about 4 hours of direct sunlight and the reminder of the day the pool is shaded by the trees. The pool is a 24 foot circular above ground pool, 52 inches deep. The volume is approximately 14,000 gallons of water.
Solar heating Approach:
Some solar heating systems reuse the filter pump to circulate the water through a solar concentrator. The downfall of this approach is two fold: 1) the filter pump has to run during the warming daytime hours and 2) the filter pump should be shut down at night so the we don’t give up the days warming gains to the cooler night.
Another disadvantage about using the filter pump is that it loads the filter system will additional pumping burden. Also the speed of the pumped water is too fast to effectively absorb the solar heat.
I used a low volume (1.5 gallons/minute) diaphragm pump (model: shurflo-8005-733-255) circulate the water through my solar array. During the typical sunlight hours I see about a 20 degree Fahrenheit temperature increase at a volume of 1.5 gallons/minute. My calculations indicate that this is approximately 120,000 BTUs of heating power.
I set the pump to a timer to trigger at 11:00 AM when the sunlight heats my solar panel and it shuts down at 4:30PM when the panel is mostly in the shade. I also use a solar cover during the overnight hours to keep the water from cooling due to evaporation. This method is especially helpful during the end of the swimming season when the nights get cooler.
Please see the photos for a description of the actual solar array.
Solar Heating Results:
Using the methods described above my swimming pool maintained a temperature of approximately 80 84 degrees Fahrenheit all summer long. It is currently September 4th and the water is still 80 degrees. -Very comfortable for swimming.